Lighting apparatus having analog-to-analog signal converter

ABSTRACT

The invention provides a system of generation of multi-channel analog output signals, from a single analog input signal, and the controlled activation of peripheral devices responsive to the multi-channel analog output signals. A single-channel to multi-channel analog-to-analog converter is provided to convert the single analog input signal to multiple output channels. Uni-directional coupling is used for coupling and mixing the multi-channel outputs and transferring the mixed outputs to a data bus. Signals on the data bus are used to drive the multiple peripheral devices.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.12/484,030 filed 12 Jun. 2009 entitled ANALOG-TO-ANALOG LIGHTINGAPPARATUS AND METHODS, which is a continuation of U.S. application Ser.No. 12/031,452 filed 14 Feb. 2008 entitled SYSTEM OF MULTI-CHANNELANALOG SIGNAL GENERATION AND CONTROLLED ACTIVATION OF MULTIPLEPERIPHERAL DEVICES. This application claims the benefit of U.S.Application No. 60/927,122 filed 2 May 2007, the content of which ishereby incorporated by reference.

FIELD OF THE INVENTION

The invention relates generally to the field of controlling multipledevices. In particular, the invention relates to a system of generationof multi-channel analog output signals, from a single analog inputsignal, and controlled activation of multiple peripheral devicesresponsive to the multi-channel analog output signals.

BACKGROUND OF THE INVENTION

Currently, digital technologies are widely used in information andcommunication applications. While digital representation of informationmay provide improved precision, human sensory functions are believed tobe fundamentally analog in nature. Frequently, information, althoughrepresented in digital form, is communicated to human users in analogform. For example, it is routine to digitize an image but present theimage on a display device, with digitized signal strength converted tobrightness of a light emitting element of the display device.

As is generally known, digitized signals are typically represented indiscrete elements, such as bits. The relative range and resolution of asignal that can be represented in digital form are limited by the numberof bits used to represent signal strength. Increasing the number of bitsincreases the range and resolution of the signal that can be representedin digital format. However, demand on data storage, data transmissionand data generation also increases as more bits are used. Simplyincreasing the number of bits therefore may impose an unacceptableburden on energy consumption, data processing capability, andrequirements on data transmission bandwidth and data storage.

SUMMARY OF THE INVENTION

Briefly, the invention relates to a system that generates multi-channelanalog output signals from a single analog input signal. The inventionalso relates to controlled activation of multiple peripheral devicesresponsive to multi-channel analog output signals so generated. Thesystem includes a single-channel to multi-channel analog-to-analogconversion engine, a uni-directional coupling unit that provides auni-directional coupling of output signals of the conversion engine to amulti-channel data bus but inhibits any feedback of information from thedata bus, and a drive module that interfaces the signals on the data busto the peripheral devices to achieve controlled activation of theperipheral devices responsive to signals on the data bus.

In a first aspect of the invention, there is provided a system forcontrolling a group of peripheral devices responsive to variation of asingle analog input signal within a range. The system includes asingle-channel to multi-channel analog-to-analog signal converter forconverting the single-channel analog input signal to a plurality ofanalog signals, the range being partitioned into a plurality ofsub-ranges, a data bus having a plurality of bus lines, each of the buslines being operatively connected to one peripheral device of the groupof peripheral devices for controlling operation thereof; and auni-directional coupling unit, the uni-directional coupling unitoperatively transmitting each of the plurality of sub-range analogsignals to at least one of a plurality of bus lines of the data bus andinhibiting any feedback from the bus being transmitted to theanalog-to-analog signal converter. The analog-to-analog signal converterhas a plurality of sub-range signal generators, each of the plurality ofsub-range signal generators being responsive to the analog input signalwithin a sub-range of the plurality of sub-ranges to generate asub-range analog signal. The sub-range signal generators may compriselinear amplifiers.

In a feature of this aspect of the invention, each sub-range signalgenerator comprises a first circuit path and a second circuit path. Thefirst circuit path is responsive to the analog input signal within thesub-range and tends to cause an output of the signal generator togradually increase in response to increase of the analog input signalwhen the analog input signal is in the sub-range. The second circuitpath is responsive to the analog input signal within the sub-range andtends to cause the output of the signal generator to gradually decreasein response to increase of the analog input signal when the analog inputsignal is in the sub-range. The first circuit path and the secondcircuit path cooperate to generate the sub-range analog signal in thesub-range.

In another feature, the analog-to-analog signal converter comprises alight source and a plurality of light detectors. Each of the pluralityof light detectors corresponds to one of the plurality of sub-ranges.Detection of light from the light source by the each light detectorproduces the sub-range analog signal. The plurality of light detectorsare spaced from each other, the light source is movable relative to theplurality of light detectors, and the relative movement is responsive tothe analog input signal.

In yet another feature, the analog-to-analog signal converter comprisesa first magnetic coupling element and a plurality of secondary magneticcoupling elements, each of the plurality of secondary magnetic couplingelements corresponding to one of the plurality of sub-ranges, theplurality of secondary magnetic coupling elements being spaced from eachother and from the first magnetic coupling element, the first magneticcoupling element being movable relative to the plurality of secondarymagnetic coupling elements, the relative movement being responsive tothe analog input signal, and variation of coupling between the firstmagnetic coupling element and the each secondary magnetic couplingelement producing the sub-range analog signal.

In another feature, the uni-directional coupling unit comprises aplurality of diodes, each of the plurality of diodes coupling an outputterminal of one of the plurality of sub-range signal generators to atleast one of the bus lines.

In yet another feature, the uni-directional coupling unit comprises aplurality of photo-electric couplers, each of the plurality ofphoto-electric couplers coupling an output terminal of the each of theplurality of sub-range signal generators to at least one of the buslines.

In other aspects the invention provides various combinations and subsetsof the aspects described above.

BRIEF DESCRIPTION OF THE DRAWINGS

For the purposes of description, but not of limitation, the foregoingand other aspects of the invention are explained in greater detail withreference to the accompanying drawings, in which:

FIG. 1 is a block diagram illustrating components of a system accordingto an embodiment of the present invention;

FIG. 2 illustrates an input analog signal within its range of variationand multiple analog output signals generated from the input analogsignal;

FIGS. 3A, 3B and 3C are schematic diagrams illustrating ways to divide avoltage range into different sub-ranges;

FIGS. 4A through 4C are schematic diagrams illustrating three differentways of constructing a sub-range signal generator;

FIGS. 5A through 5D are schematic diagrams illustrating some possibleconnections to couple an analog-to-analog signal converter to a databus;

FIG. 6 illustrates schematically a gate/interface component constructedfrom transistors for driving three LEDs using signals on three buslines;

FIG. 7 is a schematic diagram showing a complete system as analternative embodiment to that shown in FIG. 1;

FIG. 8 shows an alternative construction of an analog-to-analog signalconverter that can be used in the system described herein, twoembodiments of which are illustrated in FIG. 1 and FIG. 6; and

FIG. 9 shows yet another alternative construction of an analog-to-analogsignal converter that can be used in the system described herein, twoembodiments of which are illustrated in FIG. 1 and FIG. 6.

DETAILED DESCRIPTION OF EMBODIMENTS

The description which follows and the embodiments described therein areprovided by way of illustration of an example, or examples, ofparticular embodiments of the principles of the present invention. Theseexamples are provided for the purposes of explanation, and notlimitation, of those principles and of the invention. In the descriptionwhich follows, like parts are marked throughout the specification andthe drawings with the same respective reference numerals.

FIG. 1 illustrates schematically components of a system according to anembodiment of the present invention. As shown in FIG. 1, the system 100has an input module 102. The input module receives as input asingle-channel analog signal. The single-channel analog signal is thenprocessed by a single-channel to multi-channel analog-to-analog signalconverter 104 to convert the single-channel analog signal to multipleanalog signals. The analog-to-analog signal converter 104 has multipleoutput channels. Each of the multiple output channels corresponds to oneof the multiple output analog signals. The output analog signals may beelectric current, for example. They may also be variations in electricvoltage, as an increase or decrease from a neutral value. Or, they maybe intensity of light beams. A uni-directional coupling unit 106 betweenthe analog-to-analog signal converter 104 and an analog data bus 108transmits the multi-channel analog signals to the analog data bus 108but inhibits any feedback from the data bus 108 to the analog-to-analogsignal converter 104. This provides a one-way coupling between the databus 108 and the analog-to-analog signal converter 104. Conveniently, theuni-directional coupling unit 106 may also combine the multi-channelanalog signals from different channels in different mixing arrangementsprior to transmitting the mixed signals to the data bus 108. Operationor activation of the peripheral devices (not shown in FIG. 1) iscontrolled by signals supplied by each bus line of the data bus 108. Anoptional gate/interface component 110 may be disposed between data bus108 and peripheral devices to enable the information, i.e., signals onthe data bus 108, to be utilized by a wide range of peripheral devices.

In one embodiment, the input analog signal is a voltage value of aninput source. Conveniently, this input analog signal can be supplied tothe system through a power supply wire. An optional DC (direct current)overflow circuit 112 is provided that is coupled to both theanalog-to-analog signal converter 104 and the input module 102. Theoverflow circuit 112 passes power supply voltage to the analog-to-analogsignal converter 104 to power its operation. The overflow unit 112 alsoallows a margin voltage extracted from supply voltage, namely a portionof the supply voltage in excess of the system's internal regulatedvoltage, to be used as input, thereby allowing a single wire control andpowering of the entire device or system. The internal regulated voltageis lower than the supply voltage and is used as a reference voltage forthe overflow unit 112 to extract the margin voltage.

As described above, the input module 102 accepts as input asingle-channel analog signal. Input is generally an analog, continuoussignal. The input signal may be a continuous voltage or current signalrepresenting (i.e., converted from) a variety of monitored signals, suchas temperature, speed, relative position, ambient brightness, or appliedforce. The input signal also may be stepped or a composition of signals,represented in a cumulated analog form, such as an accumulated unitnumber from a production line. The input also may be a manuallyadjustable electric voltage or current. The analog signal may take theform of alternating current (AC), direct current (DC), value of avariable resistor (VR), or as a photoelectric input (PE), just to name afew examples. Conveniently, converters to convert one type of inputsignal, such as temperature, sound or speed, to another type of signal,such as electric current or voltage, can be provided in the input module102.

The single-channel analog signal varies within a range, between aminimum and a maximum value. The range can be partitioned into a numberof sub-ranges, the union of all sub-ranges being the range of the analogsignal. Each of the sub-ranges overlaps with its neighbors, though it isunderstood that at either end of the range a sub-range has only one andtherefore can only overlap with one neighbor. FIG. 2 illustrates asingle channel signal V_(IN) varying linearly within a range 200. Range200 is partitioned into sub-ranges R₁ (202), R₂ (204), R₃ (206), R₄(208), . . . , R_(N) (210), N being the total number of sub-ranges,which can be any integer number. Each sub-range can be any value, asrequired by the application. These sub-ranges each overlap with theirrespective neighboring sub-ranges. For example, the sub-range R₂overlaps with both its neighbor R₁ at its lower end (lower overlapregion 212) and R₃ at its upper end (upper overlap region 214).

As V_(IN) varies within the range 200, the system 100 generates, as anintermediate step, a multiplicity of output analog signals, namely V₁,V₂, V₃, V₄, . . . , V_(N), corresponding to the sub-ranges. In otherwords, the system 100 maps an analog input (V_(IN)) in a single channelto outputs of multiple channels (V₁, V₂, V₃, V₄, . . . , V_(N)). Themapping is typically continuous. Each output analog signal is mappedfrom the variation of V_(IN) within its corresponding sub-range R₁(202), R₂ (204), R₃ (206), R₄ (208), . . . , R_(N) (210), to V₁, V₂, . .. , V_(N), as V_(IN) increases from a lower bound of a sub-range to anupper bound of the sub-range. The variation of V_(i) in itscorresponding sub-range V_(i) defines a waveform 216. For example, asV_(IN) increases, the output signal 216 corresponding to a sub-rangeV_(i) increases gradually from its initial value (for example, zero) inan up-take region 218 until it reaches a peak value. The output signal216 may remain generally constant in a portion of the sub-range asV_(IN) continues its increase (thereby forming a peak region 220) andthen decreases gradually, generally back to (but not necessarily) itsinitial value (forming a decay region 222). The up-take region 218, peakregion 220 and decay region 222 together form a profile of the outputsignal, or “wave form” of the output signal. The durations of each ofup-take region 218, peak region 220 and decay region 222 are adjustable,as will be described later in more detail in examples provided below.For example, up-take region 218 may have a duration longer than thedecay region, or vice versa. The increase in the up-take region 218 andthe decrease in the decay region do not need to be linear, and can takeany shape, or even with reflection points, as long as the general trendremains generally increasing or decreasing. Similarly, the peak region220 may have any duration and may be absent (zero duration) and is notnecessarily flat.

One example of output analog signals is illustrated in FIG. 2. Outputsignals illustrated in FIG. 2 all have an approximate trapezoidal waveform 216. As the input sweeps through its own range 200, each of theoutput channels in its corresponding sub-range V_(i) also generates acorresponding output analog signal. As illustrated in FIG. 2, theup-take region 218 of one wave in one channel overlaps with the decayregion 222 of the wave of the previous channel. The overlap of theup-take and decay regions of neighboring sub-ranges (or neighboringchannels) leads to a smooth transition of signals from one channel tothe next in a transition region. A transition region is the portion ofneighboring sub-ranges where they overlap. In addition to partialoverlap, there also can be complete overlap, i.e., simultaneous turningon of multiple channels. Similarly, as V_(IN) increases from its lowerbound to its upper bound, an output channel may be responsive to V_(IN)in more than one sub-ranges and generate more than one wave form 216.FIG. 2 shows two such simultaneous “ON” signals, 216′, 216″, in channelsV₂ and V₃, with two wave forms in each channel.

The output analog signals are generated by the analog-to-analog signalconverter 104. Conveniently, the analog-to-analog signal converter (orthe input module itself) partitions the input range 200 into multiplesub-ranges. FIGS. 3A, 3B and 3C provide three examples of partitioning avoltage range. As will be appreciated, there are numerous methods topartition (or, where there is no overlapping, to divide) a voltage rangeor current range into a selected number of sub-ranges. FIG. 3Aillustrates schematically a method of dividing a voltage range intomultiple sub-ranges using a series of diodes D_(A), D_(B), D_(C), D_(E)etc. with voltage outputs at nodes V_(A), V_(B), V_(C), V_(D) etc. FIG.3B provides another example, in which sub-ranges determined by diodesD_(A) and D_(B) are further divided using voltage dividers consisting oftwo resistors each, thus providing narrower sub-ranges with voltageoutputs at nodes V_(A), V′_(A), V_(B), V′_(B), V_(C), V_(D) etc. Itshould be noted that while two resistors are shown, a voltage dividerconsisting of resistors may use any number of resistors. FIG. 3Cillustrates another example of voltage dividers consisting of two railsof diodes, each rail being connected in series. Voltage output at V_(I)and voltage output at V_(J) are adjustable by varying values ofresistors connecting the respective voltage outputs to different dioderails, thereby providing even more refined voltage differences betweenvoltage outputs V_(I) and V_(J).

Conveniently, the analog-to-analog signal converter 104 provides asub-range signal generator 400 for each sub-range. The waveform withineach sub-range is determined by the construction of the correspondingsub-range signal generator 400. The width and position of a sub-rangecan be further fine tuned by adjusting component properties of circuitcomponents employed in the corresponding sub-range signal generator 400.

Referring to FIG. 4A, there is illustrated schematically a sub-rangesignal generator 400 constructed from bipolar junction transistors andresistors. The sub-range signal generator 400 shown in FIG. 4A comprisestwo NPN bipolar junction transistors T₁ and T₂. The base of each bipolarjunction transistor is connected through a current limiting resistor R₁,R₂ to the output of a voltage divider. The voltage divider provides areference voltage such as V_(A) or V_(B). If the sub-range signalgenerator 400 is connected to V_(A) and V_(B) of a sub-range dividershown in FIG. 3A, the voltage difference between the connectors V_(A)and V_(B) of sub-range signal generator 400 is approximately the voltagedrop across diode D_(A), or approximately 0.6V. If the sub-range signalgenerator 400 is connected to V_(A) and V′_(A) of a sub-range dividershown in FIG. 3B, the voltage difference between the connectors V_(A)and V_(B) of sub-range signal generator 400 is a fraction of the voltagedrop across diode D_(A), i.e., less than 0.6V. For the purpose ofillustrating the operation of the sub-range signal generator 400, thefollowing description assumes that transistors T₁ and T₂ are connectedto a sub-range divider as shown in FIG. 3A.

Each of the transistors T₁, T₂ is part of a circuit path in thesub-range signal generator 400. The first circuit path 402 comprisestransistor T₁ and its base current limiting resistor R₁. The basecurrent limiting resistor R₁ is connected to sub-range output V_(A),i.e., directly to the input voltage, V_(IN). The second circuit path 404comprises transistor T₂ and its base current limiting resistor R₂. Thebase current limiting resistor R₂ is connected to sub-range outputV_(B), i.e., at a level approximately 0.6V lower than V_(A). The firstcircuit path 402 drives the load resistor R_(L), supplying the currentsource for the signal at the resistor R_(L). The second circuit path 404is a shunting path to ramp off the first circuit path 402 and thereforemay also be regarded as a self-shunting circuit path.

Referring to FIG. 4A and FIG. 3A, the operation of sub-range signalgenerator 400 is now described in further detail. As the input voltage,V_(IN), increases from 0, transistor T₁ becomes forward biased. Thisprovides a biasing current to enable T₁ to first operate in its linearamplification region. This allows a collector current of transistor T₁to flow through load resistor R_(L) and produce an output voltage signalV_(OUT) proportional to the biasing current. This current flowingthrough R_(L) and T₁ increases monotonically in the linear amplificationregion of T₁ up to a desired high point determined by the value ofResistor R_(I), i.e., the circuit path is in the pulled on state, atwhich point the current flowing through T₁ reaches a plateau. This formsthe up-take region of the waveform 216.

The bipolar junction transistor T₁ may remain in the high state for somerange of values of the input, thereby forming the peak region 220.Meanwhile, as input voltage continues its increase, V_(B) will start toincrease and will eventually overcome the voltage drop across diodeD_(A) and provide a forward biasing for the second transistor T₂. Thisrepresents the on-set of ramping off of the first circuit path 402. Asthe input continues to increase, the collector current of T₂ willincrease. However, any current flowing through the collector of T₂shunts the current flowing into the base of transistor T₁, thusgradually returning T₁ from its maximally conducting state to its linearregion, until T₂ becomes maximally conducting. Thus, as the currentthrough T₂ increases, the current through T₁ decreases. This forms thedecay region of the waveform 216 and completes the output waveform shownin FIG. 2.

In other words, while transistor T₁ in the first circuit path 402provides pull-on of signal, i.e., current in R_(L), transistor T₂ in thesecond circuit path 404 provides a self-shunt, pull off of the firstcircuit path 402. The on-set of pull-on determines the lower bound ofthe sub-range. The complete pull off effected by the ramping on of thesecond circuit path 404 determines the upper bound of the sub-range. Thedelayed ramping on of the second circuit path 404 cooperates with thepull on of the first circuit path 402 to produce a desired profile ofthe output waveform. Both the width and the position of the sub-rangeare affected by the sub-range voltage outputs at, for example, V_(A),V_(B), and by values of the base resistors, R₁ and R₂, and therefore canbe adjusted by adjusting characteristic values of these circuitelements. For further adjustment, emitter resistors may also be added toeach of the transistors to fine tune the range and overlap. It will beappreciated that adjusting the profile in one sub-range also changes theoverlap with profiles of neighboring sub-ranges when the profiles of theneighboring sub-ranges remain the same.

As described above, each sub-range has a corresponding sub-range signalgenerator 400. Referring to FIG. 3A, the difference between voltageoutputs V_(B) and V_(C), namely, a voltage drop across diode D_(B),corresponds to another sub-range. Another sub-range signal generator400′ (not shown in FIG. 1; but see FIG. 7) is connected to voltageoutputs V_(B) and V_(C). As bipolar junction transistor T₂ in thesub-range signal generator 400, connected between V_(A) and V_(B),starts to shunt current, signal in the next sub-range, a sub-rangedefined by V_(B) and V_(C), is activated in that transistor T₁′ ofconverter 400′ starts to allow current to flow, following the profile ofan up-take region 218 of an output waveform, until it reaches its peak.As input voltage continues to increase, T₁′ will be ramped off by itscorresponding second circuit path in the converter 400′ in a decayregion 222. Meanwhile, the output signal of the next sub-range willstart its up-take growth. This process will repeat for each sub-range asthe input value continues to increase, as illustrated in FIG. 2 anddescribed earlier.

The combination of the voltage divider portion and the series ofsub-range signal generators 400 forms an analog, self-shunting DCvoltage/current ladder. The ladder can be of any length. In other words,range 200 of input signal can be of any value and can be partitionedinto any number of sub-ranges. As the input varies from its minimum toits maximum, a wave having the waveform 216 transitions from the loweststep, namely the lowest sub-range, progressively, to the top of theladder, namely the highest sub-range.

As will be appreciated, voltage dividers may be conveniently formedusing resistors, or any other suitable means, not necessarily diodes.For example, a voltage divider consisting of only resistors can be usedto replace the string of diodes in FIG. 3A. Any number of resistors canbe used in such a resistor divider ladder. Such a resistor ladder canprovide finer voltage drops at each step of the ladder. Similarly,although a sub-range generator 400 shown in FIG. 4A provides a circuitexample using discrete transistors, other devices, such as linear gates,logic diode gates, comparators, among others, may replace thetransistors circuitry for constructing the single-channel tomulti-channel analog-to-analog converter.

FIG. 4B shows an example, in which the voltage divider 410 is formedfrom resistors connected in series and the conversion of input analogsignal in each sub-range is provided by two op-amps 1A, 1B connected incascade. In this example, the first op-amp 1A and in second op-amp 1Bcooperate to provide ramp-on and the second op-amp 1B and an op-amp 2Aof the next sub-range provide ramp-off. Consider the case where V_(IN)is initially at zero, which sets the negative terminal 414 of the firstop-amp 1A at level “L”. The resistor ladder is configured to set eachsub-range at 0.1V, though it will be understood that each sub-range (orsub-range generator) can be configured to have any value (for example,several volts or more if necessary or a few millivolts or less ifrequired). The positive terminal 412 of the first op-amp 1A is at 0.1V,a voltage supplied by the voltage divider 410. Consequently, the outputterminal 416 of the first op-amp 1A is at level “H”, so is the positiveterminal 418 of the second op-amp 1B, which is electrically connected toand at the same level as the output terminal 416 of the first op-amp 1A.The negative terminal 420 of the first op-amp 1B is also electricallycoupled to and at the same level as the output terminal of the secondop-amp 2A, which is also at “H”. Consequently, the output terminal 422of the second op-amp is initially at “H”.

As V_(IN) increases and exceeds 0.1V, the first output terminal 416 isfirst set to “L” which subsequently toggles the output level of secondop-Amp 1B and sets the second output terminal 422 to “L”. As V_(IN)continues to increase, but still remains smaller than the 0.2V, thesecond op-Amp 2A the level at the second output terminal 422 remains at“L”. When V_(IN) exceeds 0.2V, the second op-amp 2A is switched to “L”,which causes the second op-amp 1B to switch off the first channel andreturns the output at the second output terminal 422 to “H”. Theresistors R_(1A), and R_(1B) connected between the output and negativeterminals of the op-amps 1A, 1B, respectively are to configure theop-amps 1A and 1B to operate also in the linear region, in addition tobeing able to switch between “H” and “L” levels.

In another embodiment, a sub-range signal generator 400 is constructedfrom logic gates. FIG. 4C provides such an example. The operation of thesignal generator constructed from logic gates is similar to that shownin FIG. 4B, described above. In FIG. 4C an input signal is presented at430. A resulting current flows to a current sink (not shown in FIG. 4C)by way of a chain of diodes 431 and a resistance 432. Voltage is droppedacross each diode 431. Thus, for a fixed input signal, the voltage atany one of nodes 433 increases as one moves from node 433A toward node433E. The voltage at each node 433 also depends on the input signal.Outputs 435 are each driven by a circuit 436 made up of NAND logic gates437 and 438.

Consider the case where the input signal increases over time from asmall valve. Resistors 439A and 439B divide the voltage differencebetween the output of gate 437 and node 433A at node 440, which isconnected to both inputs of gate 437. The output of gate 437 isinitially high (since the voltage at node 433A is initially low). Theoutput of gate 437 connects to one input 442A of gate 438. The otherinput 442B of gate 438 is connected to the output of a voltage dividermade up of resistors 443A and 443B. Therefore, the output of gate 438 isinitially high. As the input signal increases, the voltage presented atinput 442B increases to a point at which the output of gate 438 beginsto decrease. As the input signed continues to rise, the voltage rises atthe inputs to gate 437 until eventually the output of gate 437 begins togo low. When this occurs, the output of gate 438 begins to go highagain. This same pattern occurs for each of circuits 436 but is shiftedrelative to the input signal.

The output signals of all sub-range signal generators 400 form theoutputs of the analog-to-analog signal converter 104, each sub-rangecorresponding to a unique channel. Referring to FIG. 1, themulti-channel outputs of the analog-to-analog signal converter 104 aretransmitted to data bus 108 through a uni-directional coupling unit 106.The uni-directional coupling unit 106 allows signals (i.e., information)from the analog-to-analog signal converter 104 to be coupled to the databus 108 but does not permit electric signals on data bus 108 to becommunicated back to the analog-to-analog signal converter 104. In oneembodiment, the uni-directional coupling unit 106 comprises a diodearray 500. Information at the output of the analog-to-analog signalconverter is communicated to data bus 108 via the diode array 500.Because of the uni-directional characteristics of diodes, no informationfrom data bus 108 is transmitted back to the analog-to-analog signalconverter 104.

FIG. 5A illustrates one arrangement, where output from each channel iscoupled to a single bus line, i.e., one of bus lines L₁, L₂ and L₃ ofthe data bus 108. Similarly, information from a single output channelcan be coupled to multiple bus lines of the data bus 108, for drivingmultiple peripheral devices each connected to a bus line. When a signalfrom each bus line drives a color LED, sending a signal from one outputchannel to multiple bus lines can provide color mixing. FIG. 5Billustrates an arrangement, in which output V_(M) is coupled to morethan one bus line, thereby driving more than one device, which can beused for color light mixing. The example in FIG. 5B shows a coupling totwo bus lines L₁ and L₂. FIG. 5C illustrates an arrangement in whichoutput V_(N) is coupled to three bus lines L₁, L₂ and L₄. On the otherhand, signals from different output channels can be combined andtransmitted to a single bus line, so that the peripheral deviceconnected to that bus line is driven by a composite signal mixed frommore than one output channel. For example, in the example shown in FIG.5B, output V_(M) is combined with a signal from output V₁ at bus lineL_(I) and a signal from output V₂ at bus line L₂.

FIG. 5D provides another example. The embodiment illustrated in FIG. 5Dhas more output channels than bus lines, or more output channels thanperipheral devices. As shown in FIG. 5D, there are three bus lines, eachfor connecting to a light emitting diode (LED) of a distinct color.These bus lines are labeled R for red color, G for green color and B forblue color. Signals V_(out1), V_(out2) and V_(out3) are each connected,through diodes D₁, D₂ and D₃, to one of R, G, B bus lines, respectively.Signal V_(out4) is transmitted to both R and G bus lines, through diodesD₄ and D₄′, respectively, thereby providing a mixing of V_(out4) withsignal V_(out1) at R bus line and a mixing of V_(out4) with signalV_(out2) at G bus line. Similarly, signal V_(out5) is transmitted to allthree R, G and B bus lines, through diodes D₅, D₅ƒ and D₅″,respectively, thereby providing a mixing of V_(out5) with signalV_(out1) at R bus line, a mixing of V_(out5) with signal V_(out2) at Gbus line, and a mixing of V_(out5) with V_(out3) at B bus line. Similaror other manners of connecting to the data bus 108, namely to its buslines R, G or B or any combinations of the bus lines, may be made forother output signals from other output channels.

The selection of diodes and connection to different bus lines depends onthe designation of each individual output channel. For example, in theexample illustrated in FIG. 5D, V_(out4) is designated as R/B mixing,i.e., mixing of R and B signals. Two diodes are provided, eachconnecting the R/B channel to one of R and B data lines, respectively.Similarly, V_(out5) is designated as R/G/B mixing. Three diodes areprovided, to connect output of the R/G/B channel to each one of R, G andB bus lines, respectively. Resistors may be used, for example, connectedin series with the diodes, to control mixing ratios. It will beunderstood that in other applications, an output channel may represent amixing of more than three signals in these situations. More than threediodes therefore may be necessary in these situations to connect anoutput channel to the data bus, each diode coupling the output channelto one of these bus lines.

FIG. 5D also shows an additional output channel, V_(out6), that iscoupled to the R bus line only. This provides a return to the initialcolor as an input signal varies from its minimum to its maximum. As asignal on each of the bus lines varies from a minimum (typically zero)to a peak and then back to the minimum, brightness of R, G, B lights,such as LEDs, packaged in a lighting unit housing, also varyaccordingly. As the input value varies from the minimum to the maximum,the color of light emitted from the lighting unit changes continuouslyfrom, for example, red to green and then to blue, covering all colors inthe spectrum from the red light when the input value is the smallest, tothe blue color when the input value is the largest. The connection ofthe final output channel to the R bus line allows the LEDs, startingfrom red, transitioning to other colors as the input analog signalvaries from its minimum to maximum, to return to red, the initial color.

As another example, a further “white” data bus line L_(w) may beprovided, for coupling to signal V_(w), that is generated when the inputhas a value between that to generate V_(OUT5) and V_(OUT6). A signal onthe bus line L_(w) controls a white color LED. Thus, when V_(IN)increases within its range, the color of light varies from red to green,from green to blue, from blue to white and then back to red. Othermethods of providing white light also may be used to generate this colorsequence. For example, “white” may be generated by mixing suitableamounts of red, green and blue colors. Empirically, it is found that aR:G:B ratio of 30:59:11 produces an acceptable “white” color asperceived by human eyes (“perceived white”).

These diodes, D₁, D₂, D₃, D₄, D₄′, D₅, D₅′, D₅″, D₆ etc. form a diodearray 500. This diode array 500 provides a one-way isolation betweenoutput channels of the analog-to-analog signal converter 104 and thedata bus 108. The uni-directionality here is provided by diodes in thediode array. The uni-directionality allows DC information to passthrough and to be transmitted to the data bus 108 but does not allow anyfeedback from the data bus 108 to be transmitted back to theanalog-to-analog signal converter 104. As will be appreciated, couplingelements other than diodes may be used for providing the one-waycoupling. Examples of uni-directional coupling units that use othercoupling elements possessing uni-directionality are provided below.

The provision of the data bus 108 helps streamlining the passing ofinformation from the analog-to-analog signal converter 104 to controlperipheral devices. In the embodiment shown in FIG. 5D, there are onlythree peripheral devices, i.e., red, blue and green colored LEDs. Eachcolor has its own corresponding bus line, namely one of R, G, and B buslines. Both splitting of signals from channels representing mixed colorsand mixing of outputs from different channels are facilitated by thedata bus 108. Signals on each bus line are passed directly to thesecolor LEDs. As will be described below, data bus 108 may also beoperatively connected to these peripheral devices through agate/interface module, which enables the system to drive an increasedrange of peripheral devices.

Although LED arrays are used in these examples to illustrate the outputcharacteristics, the signals on these bus lines can be used to driveother peripheral devices, not necessarily an LED array. For example, theLED examples provided herein illustrate the lighting of LEDs driven bythe resulting drive currents. These same currents may also be used todrive a multitude of motors, provided the driver circuitry suppliessufficient current. The motors may be used to manipulate (or control)motion of a robot, for example. These currents also can be used tocontrol operation of peripheral devices requiring input of more than onephase, such as multi-phased currents or voltages. For example, themulti-channel output signals may be conveniently used as the output of asingle phase to multi-phase converter for driving a multi-phase motor,using a single phase alternating current input. Alternatively, eachoutput channel may also drive an analog/digital converter therebyinterfacing the system with a digitally driven device, or devices. Ingeneral, driver circuitry may be provided to convert signals on the databus to drive current or voltage loads.

Optionally, a gate/interface component 110 is provided between data bus108 and peripheral devices as the driver circuitry, to enable theinformation, i.e., signals on the data bus 108, to be utilized by a widerange of peripheral devices. In one embodiment shown in FIG. 6, thegate/interface component 110 has individual bipolar junction transistorsT_(R1), T_(R2), T_(G1), T_(G2), T_(B1), T_(B2), for driving each one ofthe output phases, namely, each one of the R, G and B LEDs. Thegate/interface component 110 also includes a bipolar junction transistorthat is used to gate the entire drive circuitry. The example in FIG. 6shows two groups of bipolar junction transistors, with opposite outputpolarities. The first group comprises three transistors T_(R1), T_(G1),and T_(B1), and the second group comprises transistors T_(R2), T_(G2),T_(B2). The on/off of the entire drive circuitry is controlled by a“high” gate transistor T_(H), for gating the first group of transistors,and a “low” gate transistor T_(L) for gating the second group oftransistors, each of the gate transistors being controlled by the signalon a control bus line C.

Conveniently, for certain applications, it is desirable to use a singlewire to supply voltage to the system as the power source and to theinput module as input signal. This may be, for example, an applicationwhere three colored LEDs are used to indicate the voltage of a powersupply by changing emitted colors. A DC overflow circuit 112 extractsany excess voltage above a nominal (i.e., internal regulation) voltageof the system and provides this “overflow” to the input module 102 as aninput signal. This is illustrated in FIG. 7. The overflow circuit 112includes diodes D_(X), D_(y), . . . D_(Z) connected in series to providea voltage drop to bring the supply voltage V_(s) down to the expectedrange of input voltage V_(IN). A protective diode D couples the supplyvoltage V_(s) to the circuitry of the system 100′, to supply power atV+. An internal voltage regulator (not shown) stabilizes the voltagepowering the system 100′ at V+.

Referring to FIG. 7, a complete system 100′ according to an embodimentof the invention is illustrated with representative circuits shown foreach of the components. This is an application for driving brightness ofthree individual lights, though it will be understood that more lightscan be added easily or the circuit arrangement can be easily modified todrive other types of output devices. One common arrangement is to driveRed (R), Green (G) and Blue (B) LEDs, packaged in a single lighting unit702. Alternatively, the same circuit arrangement can be used to drivegrayscale lamps and UV or FR lamps. Grayscale lamps may be “cold white”(i.e., with a relatively stronger contribution from higher spectrum end,or with less red component than a typical “perceived white”), “perceivedwhite”, or “warm white”, respectively. The input to the system 100′ canbe taken either from a variable resistor connected between V+ and theground, or driven by the power supply voltage through a voltage overflowcircuit 112, as described above. As the input value varies from theminimum to the maximum, the color of light emitted from the lightingunit 702 changes continuously from, for example, blue to green and thento red, covering all colors in the spectrum from a blue light when theinput value is the smallest, to a red color when the input value is thelargest.

In FIG. 7, only two sub-range signal generators 400 are shown in detail.In combination, a series of diodes and the correspondinganalog-to-analog converters form a static, analog, self shunting DCvoltage/current ladder 704. As described before, a number of diodes,connected in series, partitions the entire input range into a pluralityof sub-ranges, each about 0.6V. The width and end points of eachsub-range can be further fine tuned by, for example, selecting values ofresistors employed in the analog-to-analog converter 104. Each level ofthe ladder 704 corresponds to an output channel. Each channel generatesan output signal that generally has a single peak, as that shown in FIG.2. The up-take region 218 of a channel, i.e., a sub-range, overlaps withthe decay region 222 of a previous channel, so that as the input signalincreases gradually, the overlap provides a smooth transition from theprevious channel to the now activated channel. Similarly, the decayregion 222 overlaps with the up-take region 218 of the next channel. Asthe output of the present channel fades out, the overlap between theup-take region of the present channel and the up-take region of the nextchannel provides a smooth transition to the next channel. Preferably,the combined output signal strength from neighboring channels adds up to100% so that when the lighting unit transitions from one color to theother, there is no perceivable change in light intensity.

Output of each channel is coupled to a bus line through a diode in theuni-directional coupling unit 106. The diodes for coupling each outputchannel to the data bus form a diode array 500. As described above, thediode array 500 provides a uni-directional coupling of output signalsfrom sub-range signal generators 400 to the data bus 108 and isolationof any feedback from the data bus 108. In addition, as described above,the diode array 500, with its connections to the data bus 108, alsoprovides mixing of signals from different output channels, for example,a mixing of signals from R/B channel and R channel at the R bus line anda mixing of signals from R/B channel and B channel at the B bus line.Also provided by the diode array 500, with its connections to the databus 108, is the splitting of signals from a selected output channel forcoupling to different bus lines.

Each output phase, i.e., signal from each bus line, has its own drivecircuit to drive a peripheral device, in this case, a colored LED. TheLED array 706, comprising LED diodes D_(B), D_(G) and D_(R), constitutesthe peripheral devices in this example. Each drive circuit works in itslinear amplification portion. For example, the output of the bluechannel, or signal on the blue bus line, is coupled to the base of thebipolar junction transistor T_(B), which in turn amplifies the signaland drives a blue color LED LED_(B). The intensity of drive currentcorresponds to the strength, or value of the output received from theconversion engine. As the signal on the blue bus line reaches its peak,the drive current also reaches its peak, thereby driving the intensityof blue LED to its brightest level. Similarly, LEDs of other colors,namely a green LED LED_(G) and a red LED LED_(R), are driven by theirrespective drive circuits comprising bipolar junction transistors T_(G)and T_(R).

To provide further control, a gate circuit comprising a first gatingbipolar junction transistor T_(G1) controls all drive circuits for allchannels in the gate/interface component 110. Thus, the transistorT_(G1) controlled by the control signal, can selectively decouple allperipheral devices from signals on the data bus. The control signal maybe supplied through a control bus line (not shown) or any other suitablemeans. The ability to turn on and off of the entire LED arrayfacilitates use of system 100′ to produce many visual effects, such asstrobe lighting effects. Although only one LED is shown for each phasein this example, it will be appreciated that several LEDs can beconnected in parallel, if low voltage V+ is used, or in series if highvoltage is used, or in any suitable combination of serial and parallelconnections, depending on the voltage and current requirement.

Similarly, a gating bipolar junction transistor T_(G2) is provided tocontrol the entire ladder 704. This allows selective enabling ofanalog-to-analog converters connected to the uni-directional couplingunit 106. For example, an alternative analog-to-analog converter (notshown) can be connected to the uni-directional coupling unit 106,operation of which is enabled through another gating transistor (notshown). Which analog-to-analog converter is enabled therefore depends onwhich gating transistor is ramped on. The gating transistor T_(G2)therefore provides a selection function, allowing selection of one ofanalog-to-analog converters to transmit multi-channel output signals tothe data bus.

FIG. 8 illustrates the use of an alternative analog-to-analog converter.This is a photoelectric analog-to-analog converter 800. In this example,a light source 802 is provided, movable along a path, such as an arc804. A plurality of light detectors 806 are arranged on a base 808, thelight detectors being spaced from each other. The base 808 is spacedfrom the path 804 of the light source 802. Each detector 806 is assignedto a different channel, the output of the detector being the outputvalue of the assigned channel. The light source 802 has a light beam 810of a limited, yet adjustable, width. The width of light beam 810 isselected such that it does not illuminate all light detectors 806simultaneously, though it illuminates at least two light detectors 806simultaneously. Preferably, the width of light beam 810 and the spacingbetween light detectors 806 are such that the light source 802 can atmost illuminate two detectors at the same time. As the light source 802moves from one end of the arc 804 to the other end, each of the lightdetectors 806 is first partially illuminated, fully illuminated,partially illuminated, and then not illuminated. A light detector 806 isgenerally illuminated simultaneously with its closest neighbor during atleast a part of the partial illumination period. The output values ofthe channel corresponding to the light detector 806 then follow profileslike that shown in FIG. 2. Adjusting positioning of light detectors 806relative to each other, relative to light source 802 and relative to thewidth of light beam 810 allows one to adjust the profiles of signals ofeach sub-range and the overlapping of these profiles. Alternatively, thewidth of light beam 810 can be adjusted for this purpose. In addition,while electrical signal at detector 806 may be forwarded to multiple buslines of data bus 108, multiple light detectors 108 may also be arrangedat the same location, each detector being coupled to a single bus line.When these light detectors at the same location are illuminated, signalscan be passed to all data bus lines connected to these detectors whichprovides an alternative method of activating multi-phased arrangementssimultaneously.

The output values from this conversion engine can be delivered to theanalog data bus 108 and to drive the multi-channel drive module, namelya gate/interface component 110, in the same manner as described above.In this example, the input is relative position of the light source 802in reference to each of the light detectors arranged on the base 808. Aswill be appreciated, any relative motion between the light source andthe base can be used to vary the input signal and therefore generate themulti-channel output signals. The relative position can be variedmanually, using a dial, or driven by the variation of another inputsignal, such as temperature or voltage of a power supply. The variationof relative position also can be achieved by moving the base 808relative to a fixed light source 802. Light detectors 806 also may bearranged on a wheel and the rotation of the wheel relative to the fixedlight source may be utilized for converting an analog signal to amulti-channel analog output signals. An input signal can be utilized todrive a stepper motor (not shown) to rotate the wheel, thereby drivingthe generation of multi-channel analog output signals.

It will be appreciated that conversion from a single-channel analogsignal can be achieved in many different ways, not restricted toexamples provided herein. Some further examples are provided below, forillustration. For example, magnetic coupling based on magnetic inductionmay be utilized. A magnet may be used as a primary coupling element anda number of coils may be used as secondary coupling elements. Inresponse to motion of the magnet in the vicinity of the coils, currentmay be generated in these coils as output signals. Similarly, a primarycoil can be used as a primary coupling element. A plurality of secondarycoils can be arranged in a manner similar to that of light detectorsillustrated in FIG. 8. As the primary coil with electric current flowingtherein is moved relative to the plurality of secondary coils, inducedcurrents in the secondary coils form the multi-channel outputs.

As also will be appreciated, the uni-directional coupling unit is notrequired to use diodes. Other uni-directional couplers can be used. Forexample, in one alternative embodiment, photo-electric coupling is used.This is illustrated in FIG. 9. As shown in FIG. 9, a photoelectriccoupler 900 comprising a light detector in the nature of aphotosensitive transistor 904 and a light emitting element 902, such asa white or infrared LED, replaces a diode in diode array 500. The lightemitting element 902 is driven by the output signal from theanalog-to-analog converter 104. Each photosensitive transistor 904 isconnected to data bus 108. While light emitted from the light emittingelement 902 transmits the output signal from analog-to-analog converter104 to the light detector, no signal from data bus 108 can betransmitted back to the light emitting element 902 by the photosensitivetransistor 904.

Various embodiments of the invention have now been described in detail.Those skilled in the art will appreciate that numerous modifications,adaptations and variations may be made to the embodiments withoutdeparting from the scope of the invention. Since changes in and oradditions to the above-described best mode may be made without departingfrom the nature, spirit or scope of the invention, the invention is notto be limited to those details but only by the appended claims.

1. Lighting apparatus comprising: an analog input; a single-channel tomulti-channel analog-to-analog signal converter configured to process asingle-channel analog input signal presented at the analog input toyield a plurality of analog output signals, said analog-to-analog signalconverter comprising a plurality of logic gates configured to provide aplurality of signal generators, each of the signal generators providingone of the analog output signals, each of the output signals variable inresponse to the analog input signal according to a profile associatedwith the analog output signal; and, a plurality of driving circuitsconnected to be controlled by the plurality of analog output signals,the driving circuits capable of driving light sources to emit light. 2.Lighting apparatus according to claim 1 wherein a light source of afirst type is connected to be driven by a first one of the drivingcircuits a light source of a second type different from the first typeis connected to be driven by a second one of the driving circuits. 3.Lighting apparatus according to claim 2 wherein a light source of athird type is connected to be driven by the driving circuit associatedwith a third one of the analog outputs wherein the first, second andthird types are different.
 4. Lighting apparatus according to claim 2wherein the light source of the first type comprises a light-emittingdiode configured to emit light of a first color and the light source ofthe second type comprises a light-emitting diode configured to emitlight of a second color different from the first color.
 5. Lightingapparatus according to claim 2 wherein a first one of the drivingcircuits is connected to drive at least one red light-emitting diode, asecond one of the driving circuits is connected to drive at least onegreen light-emitting diode and a third one of the driving circuits isconnected to drive at least one blue light-emitting diode.
 6. Lightingapparatus according to claim 1 comprising a plurality of light sources,different ones of the light sources operable to emit light of differentcolors, each of the light sources connected to be driven by one of thedriving circuits such that the light sources are controllable inresponse to the analog input signal to provide color mixing.
 7. Lightingapparatus according to claim 1 comprising at least first, second andthird driving circuits, wherein the first driving circuit is connectedto drive a source of red light, the second driving circuit is connectedto drive a source of green light and the third driving circuit isconnected to drive a source of blue light.
 8. Lighting apparatusaccording to claim 7 wherein a fourth one of the outputs is connected todrive at least one additional light source.
 9. Lighting apparatusaccording to claim 7 wherein the sources of red, green and blue lightcomprise light-emitting diodes.
 10. Lighting apparatus according toclaim 1 wherein the input signal represents a characteristic of ambientlight.
 11. Lighting apparatus according to claim 10 wherein thecharacteristic is a brightness of the ambient light.
 12. Lightingapparatus according to claim 1 wherein the input signal comprises anelectrical signal representing an accumulated value.
 13. Lightingapparatus according to claim 1 wherein the analog input is connected toreceive the analog input signal from a power supply wire.
 14. Lightingapparatus according to claim 13 wherein the power supply wire isconnected to supply electrical power to the single-channel tomulti-channel analog-to-analog signal converter.
 15. Lighting apparatusaccording to claim 1 wherein the input signal comprises an externallyadjustable electric voltage or current.
 16. Lighting apparatus accordingto claim 15 wherein the input signal comprises a user adjustableelectric voltage or current.
 17. Lighting apparatus according to claim 1wherein the input signal comprises a composition of signals representedin a cumulated analog form.
 18. Lighting apparatus according to claim 1wherein the input signal comprises a stepped analog signal.
 19. Lightingapparatus according to claim 1 wherein one or more of the profilescomprises a ramp region wherein an increase in the value of the analoginput signal provides a corresponding increase in the value of thecorresponding analog output signal and a peak region wherein the valueof the corresponding analog output signal remains generally constant asthe analog input signal changes.
 20. Lighting apparatus according toclaim 1 wherein one or more of the profiles comprises a decay regionwherein an increase in the value of the analog input signal provides acorresponding decrease in the value of the corresponding analog outputsignal.
 21. Lighting apparatus according to claim 1 wherein each of theprofiles has at least one energized portion wherein the value of thecorresponding output signal is non-zero and wherein the energizedportions of at least two of the profiles overlap.
 22. Lighting apparatusaccording to claim 1 wherein the single-channel to multi-channelanalog-to-analog signal converter is configured to partition an inputrange of the input signal into a plurality of sub-ranges.
 23. Lightingapparatus according to claim 22 wherein the sub-ranges each correspondto one of the outputs and, for each of the outputs, the control circuitis configured to control the corresponding output signal to be off whenthe input signal has a value outside of all sub-ranges corresponding tothe output.
 24. Lighting apparatus according to claim 22 wherein aplurality of non-overlapping ones of the sub-ranges correspond to one ofthe outputs.
 25. Lighting apparatus according to claim 22 whereinneighboring ones of the sub-ranges overlap.
 26. Lighting apparatusaccording to claim 22 wherein at least two of the sub-ranges completelyoverlap to provide simultaneous turning on of a plurality of the outputsignals in response to an increase in the input signal into the at leasttwo of the sub-ranges.
 27. Lighting apparatus according to claim 1wherein each of the profiles has at least one energized portion whereinthe value of the corresponding output signal is non-zero and theenergized portions of different ones of the profiles correspond todifferent sub-ranges of values of the analog input signal.
 28. Lightingapparatus according to claim 27 wherein at least one of the profilescomprises a plurality of distinct energized portions.
 29. Lightingapparatus according to claim 27 wherein two or more of the sub-rangesoverlap.
 30. Lighting apparatus according to claim 1 wherein one or moreof the mappings comprises a non-linear mapping.
 31. Lighting apparatusaccording to claim 1 wherein one or more of the profiles variesnon-linearly with changes in the input signal.
 32. Lighting apparatusaccording to claim 1 wherein, for at least some values of the analoginput signal, all of the analog output signals are off.
 33. Lightingapparatus comprising: an analog input; a plurality of analog outputs; acontrol circuit configured to process an analog input signal presentedat the analog input to provide analog output signals at each of theanalog outputs, the control circuit embodying mappings corresponding toeach of the plurality of analog outputs, the mappings relating values ofthe analog input signal to corresponding values of the analog outputsignals; and a plurality of light source driving circuits respectivelyconnected to be controlled by the plurality of analog output signals;wherein the control circuit comprises a plurality of logic gatesconnected to implement the mappings and the mappings are such thatchanging the value of the analog input signal within a range causes eachof the analog output signals to vary according to a profile for thatoutput signal.
 34. Apparatus according to claim 33 comprising aplurality of light sources each connected to be energized by acorresponding one of the plurality of light source driving circuits. 35.A method for controlling lighting apparatus, the method comprising:receiving a single-channel analog input signal; processing thesingle-channel analog input signal by a single-channel to multi-channelanalog-to-analog signal converter to provide a plurality of analogoutput signals according to a corresponding plurality of mappings at acorresponding plurality of analog outputs, each of the mappings relatingvalues of the analog input signal to corresponding values of one of theanalog output signals, the single-channel to multi-channelanalog-to-analog signal converter comprising a plurality of logic gatesconfigured to implement the mappings; and, applying the output signalsto control a corresponding plurality of light sources.